Field of the Invention
The present invention relates to a fuel cell stack formed by stacking an electrolyte electrode assembly and a separator in a stacking direction. The electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes. Rectangular end plates are provided at both ends in the stacking direction.
Description of the Related Art
For example, a solid polymer electrolyte fuel cell employs a membrane electrode assembly (MEA) which includes an anode, a cathode, and an electrolyte membrane interposed between the anode and the cathode. The electrolyte membrane is a polymer ion exchange membrane. The membrane electrode assembly and separators sandwiching the membrane electrode assembly make up a unit cell. In use, generally, a predetermined number of unit cells are stacked together to form a fuel cell stack mounted in a vehicle.
Mostly, the fuel cell stack of this type adopts an internal manifold structure where a fuel gas supply passage and a fuel gas discharge passage as passages of a fuel gas, an oxygen-containing gas supply passage and an oxygen-containing gas discharge passage as passages of an oxygen-containing gas, and a coolant supply passage and a coolant discharge passage as passages of a coolant extend through the unit cells in the stacking direction.
As a technique related to the internal manifold type fuel cell, for example, Japanese Laid-Open Patent Publication No. 2011-054425 (hereinafter referred to as the conventional technique 1) is known. The conventional technique 1 relates to a fuel cell stack formed by stacking electrolyte electrode assemblies and separators in a stacking direction. Each of the electrolyte electrode assemblies includes a pair of electrodes and an electrolyte interposed between the electrodes. Rectangular end plates are provided at both ends in the stacking direction.
A pair of coolant supply passages and a pair of coolant discharge passages extend through two opposite long sides of the fuel cell stack in the stacking direction as passages of a coolant. One of the end plates includes a pair of manifold sections connected to at least one pair of the pair of coolant supply passages and the pair of coolant discharge passages, and a coupling section for coupling the pair of manifold sections together. The width of the coupling section along the long sides is smaller than the width of the pair of manifold sections.
According to the disclosure, increase in the pressure loss of the coolant flowing into the manifold is suppressed effectively, and it becomes possible to supply the coolant to the fuel cells smoothly and uniformly.